During the first and third trimesters of pregnancy, the women rated their sexual function, focusing on six topics: desire, arousal, lubrication, orgasm, satisfaction, and pain.

There were slight decreases in each area between the first and third trimesters, but overall, the changes were minor.

That surprised the experts. They expected that many of the physical changes associated with pregnancy, such as a bigger abdomen and breasts, might have negative effects on a woman's sexual function and desire.

"We hypothesized that pregnancy is associated with many changes and at times difficulty," write the researchers in their abstract, which was recently presented in Philadelphia at the annual meeting of the American Society of Reproductive Medicine.